The present invention relates to machines for producing elementary cables constituted by a rigid dielectric support having grooves or slots in which optical fibers protected by a subsequent taping are placed. An optical fiber cable element of this type is described in U.S. patent application, Ser. No. 877,872, filed by the Assignee on Feb. 15, 1978 and entitled "Cable incorporating optical fibers".
The U.S. Pat. No. 4,221,513 describes a method for continuously machining grooves which are helical or have an alternating pitch in a dielectric member for forming the optical fiber support of an optical fiber cable element. The U.S. Pat. No. 4,237,687 entitled "Optical fiber laying head for cable productions" describes a device which permits the continuously simultaneous laying of all the optical fibers in the grooves of a previously machined cylindrical support. The tandem arrangement of these two stations in a continuous production line for cable elements leads to difficulties during operation due particularly to the inevitable interruptions and occur more specifically on starting up the production line. Thus, as it is explained in said U.S. Pat. No. 4,221,513 entitled "Method of continuously machining supports for electromagnetic wave guides", the grooves are machined hot, at a temperature which depends on the nature of the material forming the support. This temperature is approximately 200.degree. C. in the case of medium density polyethylene. When the machining station is stopped accidentally or deliberately, the support is immobilized and there is a local overheating of the area in the vicinity of the tool, due to the thermal inertia of the latter. Thus, it is not possible to merely recommence production by starting up the process again, because a certain length of the support will have been damaged by the overheating. It is therefore impossible to incorporate the aforementioned machining station in a production line, which has necessarily to be stopped and restarted without damaging the elements constituting the cable.